This invention relates to optical components generally, that is, components which operate in the optical domain. Such components are designed for use in various systems which utilize optical fibers, such as optical communications systems, optical data processing systems and optical switching systems. Specifically, this invention pertains to an optical serial-to-parallel converter.
The development of optical fiber and optical semiconductor technologies in recent years has made possible various types of optical communications systems and optical switching systems. To utilize the full bandwidth and speed available in optical systems, it has become necessary to design and fabricate optical logic and switching components which eliminate the necessity for electrical-to-optical and optical-to-electrical conversions.
Electronic serial-to-parallel converters have played a major role in digital electronic systems for many decades. Numerous electronic systems and subsystems have been based on them. Optical serial-to-parallel converters, on the contrary, were relatively neglected because there were few optical systems that really needed serial-to-parallel converters. This is no longer true. The deployment of optical fibers for information transmission has necessitated a different approach to this problem. At present, the high bandwidth advantage of optical fibers is still not fully utilized because electronic switching systems are not fast enough for high speed and high throughput optical switching. To solve this problem, the switching functions must be performed in the optical domain, eliminating the optical-to-electrical and electrical-to-optical conversions. Despite the rapid development of optical fiber technology, optical serial-to-parallel converters have received only scant attention. It is presently anticipated that optical serial-to-parallel converters will play an important role in optical switching systems such as self-routing optical switching systems and optical ring switching systems. In these switching systems, the use of optical serial-to-parallel converters will simplify the design of the systems and improve their performance.
In existing optical time-division switching systems, time slot interchanges are accomplished by using the demultiplexing/storing/retrieving/multiplexing procedure. Examples may be found in R. A. Thompson and P. P. Giordano, "An experimental photonic time-slot interchanger using optical fibers as reentrant delay-line memories," J. Lightwave Technology, vol. LT-5, pp. 154-162, January 1987, and H. Goto, "Photonic time-division switching technology," Technical Digest, Topical Meeting on Photonic Switching, pp. 132-134, March 1987. In this prior art optical writing gates and bistable devices are employed for demultiplexing and storing, respectively. These two types of devices may be replaced by an optical serial-to-parallel converter which performs the same functions.